Investigation of the effects of short-term inhalation of carbon nanoparticles on brains and lungs of c57bl/6j and p47(phox-/-) mice

Titanium dioxide and carbon black nanoparticles disrupt neuronal homeostasis via excessive activation of cellular prion protein signaling

Background

Epidemiological emerging evidence shows that human exposure to some nanosized materials present in the environment would contribute to the onset and/or progression of Alzheimer’s disease (AD). The cellular and molecular mechanisms whereby nanoparticles would exert some adverse effects towards neurons and take part in AD pathology are nevertheless unknown.

Results

Here, we provide the prime evidence that titanium dioxide (TiO₂) and carbon black (CB) nanoparticles (NPs) bind the cellular form of the prion protein (PrP^C), a plasma membrane protein well known for its implication in prion diseases and prion-like diseases, such as AD. The interaction between TiO₂- or CB-NPs and PrP^C at the surface of neuronal cells grown in culture corrupts PrP^C signaling function. This triggers PrP^C-dependent activation of NADPH oxidase and subsequent production of reactive oxygen species (ROS) that alters redox equilibrium. Through PrP^C interaction, NPs also promote the activation of 3-phosphoinositide-dependent kinase 1 (PDK1), which in turn provokes the internalization of the neuroprotective TACE α-secretase. This diverts TACE cleavage activity away from (i) TNFα receptors (TNFR), whose accumulation at the plasma membrane augments the vulnerability of NP-exposed neuronal cells to TNFα -associated inflammation, and (ii) the amyloid precursor protein APP, leading to overproduction of neurotoxic amyloid Aβ40/42 peptides. The silencing of PrP^C or the pharmacological inhibition of PDK1 protects neuronal cells from TiO₂- and CB-NPs effects regarding ROS production, TNFα hypersensitivity, and Aβ rise. Finally, we show that dysregulation of the PrP^C-PDK1-TACE pathway likely occurs in the brain of mice injected with TiO₂-NPs by the intra-cerebro-ventricular route as we monitor a rise of TNFR at the cell surface of several groups of neurons located in distinct brain areas.

Conclusion

Our in vitro and in vivo study thus posits for the first time normal cellular prion protein PrP^C as being a neuronal receptor of TiO₂- and CB-NPs and identifies PrP^C-coupled signaling pathways by which those nanoparticles alter redox equilibrium, augment the intrinsic sensitivity of neurons to neuroinflammation, and provoke a rise of Aβ peptides. By identifying signaling cascades dysregulated by TiO₂- and CB-NPs in neurons, our data shed light on how human exposure to some NPs might be related to AD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00490-x.

High-Throughput Screening Platform for Nanoparticle-Mediated Alterations of DNA Repair Capacity

The potential genotoxic effects of engineered nanomaterials (ENMs) may occur through the induction of DNA damage or the disruption of DNA repair processes. Inefficient DNA repair may lead to the accumulation of DNA lesions and has been linked to various diseases, including cancer. Most studies so far have focused on understanding the nanogenotoxicity of ENM-induced damages to DNA, whereas the effects on DNA repair have been widely overlooked. The recently developed fluorescence multiplex-host-cell reactivation (FM-HCR) assay allows for the direct quantification of multiple DNA repair pathways in living cells and offers a great opportunity to address this methodological gap. Herein an FM-HCR-based method is developed to screen the impact of ENMs on six major DNA repair pathways using suspended or adherent cells. The sensitivity and efficiency of this DNA repair screening method were demonstrated in case studies using primary human small airway epithelial cells and TK6 cells exposed to various model ENMs (CuO, ZnO, and Ga2O3) at subcytotoxic doses. It was shown that ENMs may inhibit nucleotide-excision repair, base-excision repair, and the repair of oxidative damage by DNA glycosylases in TK6 cells, even in the absence of significant genomic DNA damage. It is of note that the DNA repair capacity was increased by some ENMs, whereas it was suppressed by others. Overall, this method can be part of a multitier, in vitro hazard assessment of ENMs as a functional, high-throughput platform that provides insights into the interplay of the properties of ENMs, the DNA repair efficiency, and the genomic stability.

Evaluating the endothelial-microglial interaction and comprehensive inflammatory marker profiles under acute exposure to ultrafine diesel exhaust particles in vitro

Exposure to combustion-derived particulate matter (PM) such as diesel exhaust particles (DEP) is a public health concern because people in urban areas are continuously exposed, and once inhaled, fine and ultrafine DEP may reach the brain. The blood-brain barrier (BBB) endothelial cells (EC) and the perivascular microglia protect the brain from circulating pathogens and neurotoxic molecules like DEP. While the BBB-microglial interaction is critical for maintaining homeostasis, no study has previously evaluated the endothelial-microglial interaction nor comprehensively characterized these cells' inflammatory marker profiles under ultrafine DEP exposures in vitro. Therefore, the goal of this study was to investigate the in vitro rat EC-microglial co-culture under acute (24 h.) exposure to ultrafine DEP (0.002-20 μg/mL), by evaluating key mechanisms associated with PM toxicity: lactate dehydrogenase (LDH) leakage, reactive oxygen species (ROS) generation, cell metabolic activity (CMA) changes, and production of 27 inflammatory markers. These parameters were also evaluated in rat microglial and endothelial monocultures to determine whether the EC-microglial co-culture responded differently than the cerebrovasculature and microglia alone. While results indicated that ultrafine DEP exposure caused concentration-dependent increases in LDH leakage and ROS production in all groups, as expected, exposure also caused mixed responses in CMA and atypical cytokine/chemokine profiles in all groups, which was not expected. The inflammation assay results further suggested that the microglia were not classically activated under this exposure scenario, despite previous in vitro studies showing microglial activation (priming) at similar concentrations of ultrafine DEP. Additionally, compared to the cerebrovasculature alone, the EC-microglia interaction in the co-culture did not appear to cause changes in any parameter save in pro-inflammatory marker production, where the interaction appeared to cause an overall downregulation in cytokine/chemokine levels after ultrafine DEP exposure. Finally, to our knowledge, this is the first study to evaluate the influence of microglia on the BBB's ultrafine DEP-induced cytotoxic and inflammatory responses, which are heavily implicated in the pathogenesis of PM-related cerebrovascular dysfunction and neurodegeneration.

Maternal occupational exposure to carbonaceous nanoscale particles and small for gestational age and the evolution of head circumference in the French Longitudinal Study of Children - Elfe study

OBJECTIVES

To investigate the association between exposure to unintentionally emitted carbonaceous nanoscale particles (NPs) and small for gestational age (SGA), as well as head circumference (HC) at birth and at two years of age.

METHODS

Mothers from the French Longitudinal Study of Children (Elfe cohort) who worked during pregnancy were selected for our study. Data collected at birth and during follow-up (up to two years) were used. The probability and frequency of maternal occupational exposure to unintentionally emitted carbonaceous NPs was estimated using a job exposure matrix (MatPUF). Multivariate logistic regression, linear regression, and mixed models were applied to estimate any associations. Analyses were carried out depending on whether mothers stopped working during the first, second, or third trimester of pregnancy.

RESULTS

Maternal occupational exposure to unintentionally emitted carbonaceous NPs was associated with SGA in the overall study population by multivariate analysis (ORa = 1.80, 95% CI: 1.29, 2.46), as well as in sub-groups of mothers who stopped working during the second (ORa = 1.84, 95% CI: 1.13, 3.02) or third (ORa = 1.80, 95% CI: 1.10, 2.95) trimesters. There were no significant associations with HC at birth or two years of age.

CONCLUSIONS

We found a significant association between occupational exposure to carbonaceous NPs and SGA, with the effect depending on the period of exposure during pregnancy. These results should encourage further studies concerning the adverse effects of exposure to carbonaceous NPs on the development of offspring.

Tangeretin-Assisted Platinum Nanoparticles Enhance the Apoptotic Properties of Doxorubicin: Combination Therapy for Osteosarcoma Treatment

Osteosarcoma (OS) is the most common type of cancer and the most frequent malignant bone tumor in childhood and adolescence. Nanomedicine has become an indispensable field in biomedical and clinical research, with nanoparticles (NPs) promising to increase the therapeutic efficacy of anticancer drugs. Doxorubicin (DOX) is a commonly used chemotherapeutic drug against OS; however, it causes severe side effects that restrict its clinical applications. Here, we investigated whether combining platinum NPs (PtNPs) and DOX could increase their anticancer activity in human bone OS epithelial cells (U2OS). PtNPs with nontoxic, effective, thermally stable, and thermoplasmonic properties were synthesized and characterized using tangeretin. We examined the combined effects of PtNPs and DOX on cell viability, proliferation, and morphology, reactive oxygen species (ROS) generation, lipid peroxidation, nitric oxide, protein carbonyl content, antioxidants, mitochondrial membrane potential (MMP), adenosine tri phosphate (ATP) level, apoptotic and antiapoptotic gene expression, oxidative stress-induced DNA damage, and DNA repair genes. PtNPs and DOX significantly inhibited U2OS viability and proliferation in a dose-dependent manner, increasing lactate dehydrogenase leakage, ROS generation, and malondialdehyde, nitric oxide, and carbonylated protein levels. Mitochondrial dysfunction was confirmed by reduced MMP, decreased ATP levels, and upregulated apoptotic/downregulated antiapoptotic gene expression. Oxidative stress was a major cause of cytotoxicity and genotoxicity, confirmed by decreased levels of various antioxidants. Furthermore, PtNPs and DOX increased 8-oxo-dG and 8-oxo-G levels and induced DNA damage and repair gene expression. Combination of cisplatin and DOX potentially induce apoptosis comparable to PtNPs and DOX. To the best of our knowledge, this is the first report to describe the combined effects of PtNPs and DOX in OS.

Effects of neonatal inhalation exposure to ultrafine carbon particles on pathology and behavioral outcomes in C57BL/6J mice

Background

Recent epidemiological studies indicate early-life exposure to air pollution is associated with adverse neurodevelopmental outcomes. Previous studies investigating neonatal exposure to ambient fine and ultrafine particles have shown sex specific inflammation-linked pathological changes and protracted learning deficits. A potential contributor to the adverse phenotypes from developmental exposure to particulate matter observed in previous studies may be elemental carbon, a well-known contributor to pollution particulate. The present study is an evaluation of pathological and protracted behavioral alterations in adulthood following subacute neonatal exposure to ultrafine elemental carbon. C57BL/6J mice were exposed to ultrafine elemental carbon at 50 μg/m³ from postnatal days 4–7 and 10–13 for 4 h/day. Behavioral outcomes measured were locomotor activity, novel object recognition (short-term memory), elevated plus maze (anxiety-like behavior), fixed interval (FI) schedule of food reward (learning, timing) and differential reinforcement of low rate (DRL) schedule of food reward (impulsivity, inability to inhibit responding). Neuropathology was assessed by measures of inflammation (glial fibrillary-acidic protein), myelin basic protein expression in the corpus callosum, and lateral ventricle area.

Results

Twenty-four hours following the final exposure day, no significant differences in anogenital distance, body weight or central nervous system pathological markers were observed in offspring of either sex. Nor were significant changes observed in novel object recognition, elevated plus maze performance, FI, or DRL schedule-controlled behavior in either females or males.

Conclusion

The limited effect of neonatal exposure to ultrafine elemental carbon suggests this component of air pollution is not a substantial contributor to the behavioral alterations and neuropathology previously observed in response to ambient pollution particulate exposures. Rather, other more reactive constituent species, organic and/or inorganic, gas-phase components, or combinations of constituents may be involved. Defining these neurotoxic components is critical to the formulation of better animal models, more focused mechanistic assessments, and potential regulatory policies for air pollution.

Electronic supplementary material

The online version of this article (10.1186/s12989-019-0293-5) contains supplementary material, which is available to authorized users.

Exposure to Engineered Nanomaterials: Impact on DNA Repair Pathways

Some engineered nanomaterials (ENMs) may have the potential to cause damage to the genetic material in living systems. The mechanistic machinery functioning at the cellular/molecular level, in the form of DNA repair processes, has evolved to help circumvent DNA damage caused by exposure to a variety of foreign substances. Recent studies have contributed to our understanding of the various DNA damage repair pathways involved in the processing of DNA damage. However, the vast array of ENMs may present a relatively new challenge to the integrity of the human genome; therefore, the potential hazard posed by some ENMs necessitates the evaluation and understanding of ENM-induced DNA damage repair pathways. This review focuses on recent studies highlighting the differential regulation of DNA repair pathways, in response to a variety of ENMs, and discusses the various factors that dictate aberrant repair processes, including intracellular signalling, spatial interactions and ENM-specific responses.

Nose to brain delivery in rats: Effect of surface charge of rhodamine B labeled nanocarriers on brain subregion localization

Nose to brain delivery and nanotechnology are the combination of innovative strategies for molecules to reach the brain and to bypass blood brain barriers. In this work we investigated the fate of two rhodamine B labeled polymeric nanoparticles (Z-ave <250nm) of opposite surface charge in different areas of the brain after intranasal administration in rats. A preliminary screening was carried out to select the suitable positive (chitosan/poly-l-lactide-co-glycolide) nanocarrier through photon correlation spectroscopy and turbiscan. Physico-chemical and technological characterizations of poly-l-lactide-co-glycolide (negative) and chitosan/poly-l-lactide-co-glycolide (positive) fluorescent labeled nanoparticles were performed. The animals were allocated to three groups receiving negative and positive polymeric nanoparticles via single intranasal administration or no treatment. The localization of both nanocarriers in different brain areas was detected using fluorescent microscopy. Our data revealed that both nanocarriers reach the brain and are able to persist in the brain up to 48h after intranasal administration. Surface charge influenced the involved pathways in their translocation from the nasal cavity to the central nervous system. The positive charge of nanoparticles slows down brain reaching and the trigeminal pathway is involved, while the olfactory pathway may be responsible for the transport of negatively charged nanoparticles, and systemic pathways are not excluded.

Neurodegenerative and neurological disorders by small inhaled particles

The world's population is steadily ageing and as a result, health conditions related to ageing, such as dementia, have become a major public health concern. In 2001, it was estimated that there were almost 5 million Europeans suffering from Alzheimer's disease (AD) and this figure has been projected to almost double by 2040. About 40% of people over 85 suffer from AD, and another 10% from Parkinson's disease (PD). The majority of AD and PD cases are of sporadic origin and environmental factors play an important role in the aetiology. Epidemiological research identified airborne particulate matter (PM) as one of the environmental factors potentially involved in AD and PD pathogenesis. Also, cumulating evidence demonstrates that the smallest sizes of the inhalable fraction of ambient particulate matter, also referred to as ultrafine particulate matter or nano-sized particles, are capable of inducing effects beyond the respiratory system. Translocation of very small particles via the olfactory epithelium in the nose or via uptake into the circulation has been demonstrated through experimental rodent studies with engineered nanoparticles. Outdoor air pollution has been linked to several health effects including oxidative stress and neuroinflammation that may ultimately result in neurodegeneration and cognitive impairment. This review aims to evaluate the relationship between exposure to inhaled ambient particles and neurodegeneration.

Activation of Proinflammatory Responses in Cells of the Airway Mucosa by Particulate Matter: Oxidant- and Non-Oxidant-Mediated Triggering Mechanisms

Inflammation is considered to play a central role in a diverse range of disease outcomes associated with exposure to various types of inhalable particulates. The initial mechanisms through which particles trigger cellular responses leading to activation of inflammatory responses are crucial to clarify in order to understand what physico-chemical characteristics govern the inflammogenic activity of particulate matter and why some particles are more harmful than others. Recent research suggests that molecular triggering mechanisms involved in activation of proinflammatory genes and onset of inflammatory reactions by particles or soluble particle components can be categorized into direct formation of reactive oxygen species (ROS) with subsequent oxidative stress, interaction with the lipid layer of cellular membranes, activation of cell surface receptors, and direct interactions with intracellular molecular targets. The present review focuses on the immediate effects and responses in cells exposed to particles and central down-stream signaling mechanisms involved in regulation of proinflammatory genes, with special emphasis on the role of oxidant and non-oxidant triggering mechanisms. Importantly, ROS act as a central second-messenger in a variety of signaling pathways. Even non-oxidant mediated triggering mechanisms are therefore also likely to activate downstream redox-regulated events.